On Sun, Sep 22, 2019 at 4:45 PM Bill Gosper <billgosper@gmail.com> wrote:
On 2019-09-22 06:15, Joerg Arndt wrote:
Even "Peano's curve" isn't unique: Walter Wunderlich: {\"{U}ber Peano-Kurven}, Elemente der Mathematik, vol.~28, no.~1, pp.~1-10, (1973). http://sodwana.uni-ak.ac.at/geom/mitarbeiter/wallner/wunderlich/ Don't let the German scare you, just check the images.
Wow, in http://sodwana.uni-ak.ac.at/geom/mitarbeiter/wallner/wunderlich/pdf/125.pdf the 3⨉3 edge-traverser (Figur 5) is a perfect(ly confusing) hybrid of Peano's with Hilbert's! Gotta "Julianize" these. —rwg
E.g., ListLinePlot[ReIm[peano[#][[1]] & /@ Range[0/4/9/4/2, 1, 1/4/9/2/2]], Axes -> False, AspectRatio -> Automatic] tetraskelions <http://gosper.org/tetraskelions.png> (with indispensAble help from Julian. I have misunderstood his argument conventions all this time!) —rwg
For the n-dimensional version of (one of) the Peano curve(s): https://jjj.de/fxt/demo/comb/index.html#peano-ndim This is following A.\ J.\ Cole: {A note on space filling curves}, Software Practice and Experience, vol.~13, no.~12, (1983) and A.\ J.\ Cole: {A Note on Peano Polygons and Gray Codes}, International Journal of Computer Mathematics, vol.~18, no.~1, pp.~3-13, (1985). These papers win both my "horrible notation" and "most useless example" award.
Best regards, jj
P.S. regarding Peanistic curves: https://jjj.de/tmp-math-fun/all-R29-curves.pdf https://jjj.de/tmp-math-fun/all-R29-tiles.pdf View both files side-by-side.
* Bill Gosper <billgosper@gmail.com> [Sep 20. 2019 10:10]:
For decades I misapprehended Hilbert's spacefill as Peano's. Today at last, I corrected my web page: http://www.tweedledum.com/rwg/samhilbert.htm . The impetus was discovering that my blunder has been copied onto other websites. Unfortunately, with correct attribution.-} —rwg _______________________